Liquid crystal displays (LCDs) have been widely applied in electrical products. Currently, most of LCDs are backlight type LCDs which comprise a liquid crystal panel and a backlight module. According to the position of the backlight source, the backlight module can be a side-light type or a direct-light type in order to provide LCDs with backlight.
Light emitting diodes (LEDs) have several beneficial characteristics, including low electrical power consumption, low heat generation, long operational life, small volume, good impact resistance, fast response and excellent stability for emitting color light with stable wavelengths. These characteristics have made the LEDs suitable for light sources of the backlight module.
Currently, a resonant circuit has been used in an LED backlight module to be a driving circuit of LEDs. The conventional resonant circuit controls a load (such as LED) with a fixed frequency. However, the load may be varied, and alternatively, the load characteristic of the load may be considerably varied for long-term utilization. Therefore, the resonant driving circuit using the fixed frequency can not be operated in the optimum status. Furthermore, when the material of a bezel of the backlight module is metal, a parasitic capacitance of the backlight module may also affect the parameter, thus deteriorating the entire operation of the circuit. Accordingly, the circuit can also not be operated in the optimum status.
As a result, it is necessary to provide a driving circuit and a driving method of a backlight module of a display apparatus to solve the problems existing in the conventional technologies, as described above.